Autotranseormer wite heating coils



Jan. 29,1924. 1,481,876

v A; MUTscHEgLl-:R ET AL.

AUTOTRANSFORMER WITH HEATING'COILS Filed oct. 15. 1920 Patented Jan. 29, 1924.

UNITED STATES PATENT OFFICE.

ARTHUR MUTSCHELLER ANI) CHARLES FAYER, OF NEW YORK, N. Y., ASSIGNORS T0 WAPPLER ELECTRIC COMPANY, INC., A CORPORATION OF NEW YORK.

AUTOTRANSFORMER WITH HEATING GOILS.

Application filed October 15, 1920. Serial No. 417,233.

To all 'whom t may concern.'

Be it known that we, ARTHUR MU'rsoHnL- LER and CHARLES FAYER, both citizens of the United States, and residents of New York city, in the county of New York and State of New York, have invented certain new and useful Improvements in Autotransformers with Heating Coils, of which the following is a full', clear, and concise description.

Our invention relates to transformers and heating coils of the type used in X-ray work, in which the source of high tension current for energizingV the X-ray tube is a transformer, and in which the X-ray tube is provided with an electrically heated glower cathode, such as an incandescing filament.

More particularly stated, our invention relates to the positioning of and the connections for the small winding used in ap# paratus of the kind just mentioned and including a vacuum tube i provided with a glower cathode, Vfor the purpose of electrically heating the glower cathode, this winding being usually designated in this art as the heating coil.

We mount the heating coil directly upon the core of the vauto-transformer-usedas a control for the high tension transformer, the high tension transformer being the one which supplies electricity for the main discharge through the X-ray tube.

By thus mounting the heating coil upon the core of the auto-transformer, and varying the connections accordingly, we attain a number of useful objects, among which are the following:

I. We eliminate all necessity for providing a separate transformer as ameans of heating the filament, as is somtimes done, or of winding an 'additional secondary on the core of the high tension transformer. Such additional winding on the core ofthe high tension transformer is objectionable, because when the high tension currents are turned on or their voltages are varied the said additional Winding is affected, and the heating currents are therebycaused to liuctuate. I

II. We thoroughly stabilize the action of the heating filament, owing'to the 'fact that in the auto-transformerY as we use it the core is always saturated. while the device is in action. Thus we render the lament insensitive to slight variations in the line voltage, and render its action constant even when the taps controlling the auto-transformer are changed from time to time under varying working conditions, whereby the high tension transformer is subjected to different voltages.

III. We enable the incandescing filament to be energized independently of the high tension currents. This is always advantageous, because when the high tension currents for energizing the X-rayy tube and the heating currents for energizing the lilament are turned on at the same instant there is always a lapse of time before the filament becomes incandescent, and there is therefore a moment of delay before the dis charge can pass through the tube.

IV. We enable a small auto-transformer, serving as a control for the high tension transformer and also as a means for generating currents used for heating, to be mounted independently of the high tension transformer and located conveniently among the switches and various regulating devices-the auto-transformer being a device quite compact and portable.

Reference is made to the accompanying drawing forming a part of this specification, and in which the figure shows diagrammatically a system in which our device is employed.

An X-ray tube appears at l, and is provided with an anode 2, supported upon an electrode 3; also with an incandescing filament 4, serving as a glower cathode. `The electrode 3 is connected with a wire 5, leading to a secondary winding 6 of a high tension transformer 7. A wire 8 leads from the secondary winding 6 to a wire 9, the latter leading to the incandescing filament 4.

The high tension transformer 7 is provided'with a primary winding 10, and from the latter a wire llleads to the arm 12 of a switch 13. The switch 13 isprovided with a number of Contact buttons such as 14, 15, 16, the contact buttons being severally connected with wires 14a. 15, 16a, the latter being connected with a winding 17, this being the secondary winding of an autotransformer 18. The auto-transformer is further provided with windings 19, 20. Leads are shown at 22, 28andare used to supply currents to the auto-transformer.

The lead 22 is connected with a slide 2li which is movable relatively to the windings 19,20.

The lead 23 is provided with la switch Z5, and this switch is connected with a wire 26, leading to the contact button 27 of another switch 28. F rom the switch last mentioned a wire 29 leads to the primary windinglO of the high tension transformer 7.

The operator by moving the slide 24 relatively to the windings 19 and `2O, and by shifting the arm 12 of the switch 13, can vary within wide limits the voltage and amperage of the currents used for energizing the high tension transformer 7, in the manner well understood in this art.

Mounted upon the core of the' auto-transformer 18 isa winding 30, serving as a heating coil. From it a wire V31 leads to a variable resistance 32. A. wire 33 leading from the variable resistance '32 is connected with a wire 4311, the latter being grounded at 35. Our purpose in grounding the wire 34 is, first, -to preventtlie development of abnormal voltages, and particularlyl voltages which are extreme as compared with, the potential of the earth, considered as zero; and second, to connect the filament with an inexhaustible supply of electrons. A wire 36 is joined to the two wires 33 and 34, and leads therefrom to the incandescing filament 4. A wire 37 is connected with both ofthe wires 8 and`-9, and with the heating coil 30.

The auto-transformer is so proportioned and arranged lthat no mattei" when or to what extent it is energized, its core is thoroughly saturated with magnetic flux. Such 'being the case, the heating coil 30 always works to its full capacity when it is energized at all. rlhe result of this arrangement is that whenever the auto-transformer is in action, the incandescent filament glows brightly and steadily, at its highest degree of incandescence, which is thus constant while/the auto-transformer is in action.

The actionof the heating coil upon the incandescing filament is independent of the action of the high tension transformer. Thus `if the switch 25 be closed and the switch28 be left open, the heating coil 30 supplies current to the incandescing filament although the high tension transformer is not being energized. lt follows as a consequence that no matter what fluctuations inaytake place in the windings of the high tension transformer, these {iuctuations can have no effect upon the incandescence ofthe filament.

The circuit used for heating the incandescing filament may be traced as follows: Heating `coil 30, wire 37, wire 9, filament 4;, wire36, wire 33, variable resistance 32, Wire 31, back to heating coil 30.

vThe general 'action of the auto-transformer, fthe high tension transformer and the X-ray tube are too well understood to need any further description.

iiie do not limit ourselves to the precise mechanism shown, as variations may be made therein without departing from the spirit of our invention, the scope of the invention being commensurate with our claims.

Having thus described our invention, what we cla-im as new and desire to secure by LettersPatent is as follows:

1. The combination of a vacuum tubeprovided with a glower cathode to be energized by electric currents, a high tension transformer connected with said vacuum tube for the purpose of sending the main discharge therethrough, a second transformer connected with said high tension transformer for controlling said high tension transformer and for energizing the same, said second transformer being so proportioned that Vthe core thereof is magnetized to saturation whenever said second transformer is magnetized to any degree, a heating coil carried by said second transformer and energized thereby, and connections from saidheating coil to said glower cathode.

2. The combination of a vacuum tube provided with a glower cathode to lbe energized by electric currents, an auto-transformer provided with a core Aand so proportioned that said core is energized to saturation whenever said auto-transformer is energized to any degree, mechanism connected with said auto-transformer and withsaid vacuum tube and controllable by said auto-transformer for the purpose of energizing said vacuum tube, a heating coil mounted upon the core of said auto-transformer and energized thereby, and connections from said heating coil to said glower cathode.

3. rifhe combination of a vacuum tube provided with a filament serving as a glower cathode, a high tension'transformer connected with said vacuum tube for the purpose of sending a main discharge therethrough, an auto-transformer connected with said high tension transformer for the purpose of energizing and controlling said high tension transformer, and a heating coil connected with said filament for the purpose of supplying heating currents thereto, said heating coil being mounted upon the core of said auto-transformer, said autotransformer being so proportioned that the core thereof is magnetized tosaturation whenever said auto-transformer is energized to any degree.

' 4f. The combination of a vacuum tube provided With a glower cathode to be energized by electric currents, a high tension trans'- former connected 'with said vacuum tube for sending a main discharge therethrough, an auto-transformer connected with said high tension 'transformer for controlling said main discharge through said vacuum heating coil being connected with said tube, said auto-transformer being provided glower cathode in order to supply electrif with a core which is always magnetically Currents for heating said glower cathode. saturated Whenever said auto-transformer so that said gloWer cathode is always heated is energized to any extent, so that the de' to the same extent independently of the eX- 15 gree of magnetization of said core is indetent to which said auto-transformer and said pendent of variations in the extent to which high tension transformer are energized.

said auto-transformer is energized, and a heating coil mounted upon said core and ARTHUR MUTSCHELLER 10 energized by the magnetism thereof, said CHARLES FAYER. 

